Control instrument



CONTROL INSTRUMENT Filed Aug. 2e, 1955 I nue/2501,-

Patented July 9, 1935 'Douglas' H. Annin, Brookline," Mass., assigner, by mesne assignments,` to? Eldon *'Macl'e'od, Westwood, Mass., Frank A. Morrison, Newton, Mass., Cameron Macleod, BerwynyPa., Leslie Seule, Dedham, Mass.,` SullivaniA..Sarge`nt, Jr;, Needham, Mass., trustees doingbusiness as Masone.;

Neilan Regulator Company, Boston, Mass.

Application August 26, 1933, serial No. 686,943

connus... (o1. `,afrit- 1e) Thisfinventiorrfrelates to control instruments landfmore-'particularlyto an improved `means for :transmitting the movement of an elementy responsive tol the Avariable physical conditionl of j a I umediurrrt'can operating or recording means.

f Anobject' of the invention is toprovide an'inrstrument' wherein the control or record shall be directly responsive to the variable physical condition, and in which vthe movementof the ele'- v ment responsive to the` variable condition shall bei-*directly transmittedl to the operating or recording means, accurately and uniformly, and

without distortion or change of proportion.

Previous constructions of which -I am. aware 16 have not transmitted the movement accurately and uniformly enough, and as a consequence have not been satisfactory in installations-Where accurate control or recording is essential throughout the entire range of movement of the responsive 20 instrument.

In the drawing:

Fig. l is a front elevation of aninstrument embodying my invention, with parts broken away to disclose the interior;

25 Fig. 2 is an elevation of the operating mechanism;

Fig. 3 isa vertical sectional view of the mechanism shown on lines 3-3 of Fig. 1.

Fig. 4 is a plan View of part of the operating 30 mechanism with the top removed, on lines 4-4 of Fig. 3.

Before Iexplaining in detail the present invention, it is to be understood that the invention is not limited in its application to the details of 35 construction and arrangement of parts illustrated in the accompanying drawing, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology 40 or terminology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements of the prior art.

Referring tothe drawing, IIl represents a cas- 45 `ing of usual construction upon which there is mounted a suitable graduated chart II carried on spindle I2, and rotated by suitable means such as clock mechanism not shown. An index arm or pen arm I3 `is suitably supported at one end 50 and arranged to travel across chart I I in an arcuate radial direction, to record on the chart the changes in the variable condition being recorded. As is usual in a control instrument of this type, there is mounted in the casing Ill a suitable base or support I4 carrying two upright rods I5 spaced apart; upon which is mounted atriangular shaped arnifld with anapex at each rod and the third apexproviding a bearing for an operating shaft l'lfto be later described. Upon the support I4 is fixed an instrumentvresponsive 'to changes in avariable condition, such as pressure, Whichcomprises ahelically coiled Bourdon tube I8 having an end I9 fixed insaid'base HlY and a sealed mov- -able end Ztl; The tube I8 is preferably of the usual-flattened shape in'cross-section and is lconnected atits fixed end I9 by a small tube 2l toa Asource'of pressure, aV suitable container (not shown) of the material Whose pressure is being recorded or under control. `It will be understood that the tube I8 tends to Wind or unwind according to fluctuations in the pressure connected to lthe tube. 'I'he operating shaft Il is suitably journalled between the bearings in the arm It and base I4 and is located in a substantially central position within the coil of the tube I8 and preferably co-axial therewith. Operating shaft I1 is preferably enlarged between its ends into a flattened strip, and is connected by means of a member 22 to the movable end 20 of Bourdon tube I8. Member 22 is preferably composed of two parallel arms 23 engaging the `iiat sides of operating shaft I'I and slidable thereon and may be closed at both ends if desired. Member 22 is `then connected by suitable clamping means 24 to the movable end 2li of tube I8. A nut and bolt 25 is used herein for this purpose. The arms 23, while closed at their ends are made long enough to extent beyond the sides of operating shaft Il, thereby providing ample lost motion area between shaft Il and movable end 20 of tube I8. It will be noted that member 22 engages shaft II for the purpose of directly transmitting any circumferential movement of movable` end 20 of Bourdon tube I8 to said operating shaft, but is slidable on said shaft for preventing the transmission of axial and radial movement of the movable end 2i) of Bourdon tube I8 because of the lost motion means provided in said member. The index or pen arm I3 is rigidly connected to the upper end of operating shaft Il to move therewith and to record changes in pressure transmitted through Bourdon tube I8. It is understood that pen arm I3 may control valve means or other mechanism, where recording is not or radial movement of said tube. Axial or radial forces of the free end 20 of tube I8 are unable to affect the operating shaft I1 and are eliminated by the lost motion means provided for the sliding member 22. Thus the circumferential or rotary movement to free end 20 of tube I8 is transmitted to operating shaft I1 uninuenced by axial and radial forces. instrument responsive to changes in pressure is directly transmitted to the recording means and an accurate record of these changes may be secured. In my construction it is unnecessary to worry about precise co-axlalalinement of the tube and operating shaft. The construction is easily put together and taken apart and the clamp, instead of solder, allows calibration of the instrument in the field.

I claim:

1. A control instrument of the class described, having in combination, a coiled element having one end fixed and the other movable, a non-circular rotatable shaft disposed co-axially within the coil of said element, and a member engaging said shaft and attached at one end to the movable portion of said element for transmitting circum- `ferential movement of said element to said shaft,

and providing lost motion for axial and radial movement of said element.

2. A control instrument of the class described, having in combination, a helically coiled responsive element having one end fixed and the other movable, a non-circular rotatable shaft disposed In this way the movement of the-` Within the coil of said element, and a member engaging said shaft, and attached at one end to the movable portion of said element for transmitting the circumferential movement of said element to said shaft, and slidable on said shaft for providing Alost motion for axial and radial movement of said element.

3. A control instrument of the class described, havingv in combination, a helically coiled element having one end fixed and the other movable, a flat rotatable shaft co-axially disposed within the coil of said element, and a member having two parallel arms engaging the flat sides of said shaft for transmitting circumferential movement, and slidable on said shaft to provide lost motion for axial and radial movement of said element.

4. A control instrument of the class described, having in combination, a helically coiled element having one end fixed and the other movable, a non-circular rotatable shaft disposed within the coil of said element, and a member engaging said shaft and attached at one en d to the movable portion of said element for transmitting the circumferential movement of said element to said shaft, and slidable on said shaft to provide lost motion for axial and radial movement of said element, a base providing a support for the ilxed end of said element and providing bearings for the opposite ends of said shaft, and an index carried by said shaft. v

DOUGLAS H. ANNIN. 

